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Production Process (production + process)
Selected AbstractsSpecialization, Context of Production, and Alienation in the Production Process: Comments and AfterthoughtsARCHEOLOGICAL PAPERS OF THE AMERICAN ANTHROPOLOGICAL ASSOCIATION, Issue 1 2007Yung-ti Li The study of craft specialization has gone through several stages since the pioneering work of Childe, each with changing foci and emphases. The current volume marks yet another development in the field that demonstrates both discontents with existing theories and efforts to enhance and strengthen the discourse. Acting as a commentator to facilitate further discussion, the first half of my chapter addresses specific issues in individual chapters, while the second half explores another dimension of production by looking at bronze and pottery production in ancient and premodern China. Whereas some contributors examine alienability in the social role of the objects and the rights over alienation of the product, this discussion examines another form of alienation that can be considered in the study of craft production, one that is both salient and tangible in archaeological data: alienation of the manufacturing process, that is, alienation of the craft producers from their own skills. The work of Ursula Franklin on Shang bronze production is reviewed, and new studies on porcelain production at Jingdezhen and stoneware production at Yixing are incorporated to further develop Franklin's model. I argue that through examining the material patterns of the production process and the type range of finished products, alienation in the workplace can be detected archaeologically. [source] Development of a Transient Segregated Mathematical Model of the Semicontinuous Microbial Production Process of DihydroxyacetoneBIOTECHNOLOGY PROGRESS, Issue 1 2006Rüdiger Bauer For the mathematical description of the semicontinuous two-stage repeated-fed-batch fermentation of dihydroxyacetone (DHA), a novel segregated model incorporating transient growth rates was developed. The fermentation process was carried out in two stages. A viable, not irreversibly product-inhibited culture was maintained in the first reactor stage until a predetermined DHA threshold value was reached. In the second reactor stage, high final product concentrations of up to 220 g L,1 were reached while the culture was irreversibly product-inhibited. The experimentally observed changes of the physiological state of the culture due to product inhibition were taken into account by introducing a segregation into the mathematical model. It was shown that the state of the cells was dependent on the current environment and on the previous history. This phenomenon was considered in the model by utilizing delay time equations for the specific rates of growth on the primary and the secondary substrate. A comparison with reproducible measurements gave a good correlation between computation and experiment. The mathematical model was validated using independent own experimental data. A comparison with a stationary and nonsegregated model demonstrated the essential improvements of the novel model. It was deduced from the model calculations that high product formation rates of 3.3,3.5 g L,1 h,1 as well as high final DHA concentrations of 196,215 g L,1 can be obtained with a residual broth volume in the first reactor stage of 2% and a DHA threshold value in the range of 100,110g L,1. [source] Assessment of Fed-Batch, Semicontinuous, and Continuous Epothilone D Production ProcessesBIOTECHNOLOGY PROGRESS, Issue 4 2005Scott A. Frykman Epothilone D is a member of a class of potent antineoplastic natural products produced by myxobacteria. Previously, we have described a fed-batch epothilone D production process in which an adsorber resin is incorporated into the bioreactor setup to capture and stabilize the product in situ, preventing its degradation within the bioreactor. The capture of epothilone D by these relatively large resin beads enables the development of continuous and semicontinuous culturing systems incorporating bead retention mechanisms to completely retain the product within the bioreactor, increasing the epothilone D product titer by almost 3-fold in both cases over a baseline fed-batch system. These product retention strategies, described here for production of the epothilones, are generally applicable to any system using adsorber resins as a method to capture product during a microbial cultivation. [source] Heterogeneous Plasma-Producing Structures at Current Implosion of a Wire ArrayCONTRIBUTIONS TO PLASMA PHYSICS, Issue 8 2005E. V. Grabovsky Abstract Characteristic properties of the plasma production process have been considered for the case of megampere currents flowing through hollow cylindrical wire arrays of the Angara-5-1 facility. In 3-4 nanoseconds after voltage applying to the wire surfaces there appear a plasma layer. The system becomes heterogeneous, i.e. consisting of a kernel of metal wires and a plasma layer. In several nanoseconds the current flow goes from metal to plasma, which results in reducing the electric field strength along the wire. The Joule heat energy delivered to the metal before the moment of complete current trapping by plasma is insufficient for the whole mass transition to a hot plasma state. The X-ray radiography techniques made it possible to detect and study dense clusters of substance of ,1g/cm3 at a developed discharge stage. The radial expansion velocity of ,104 cm/s measured at the 70-th nanosecond after the current start allows treating the dense core at a late stage in the form of a submicron heterogeneous structure from its liquid and slightly ionized gas phase. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Managing Uncertainty in Creative Industries: Lessons from Jerry Springer the OperaCREATIVITY AND INNOVATION MANAGEMENT, Issue 3 2006Anna M. Dempster This article considers the impact of uncertainty on entrepreneurial performance in the UK theatre industry. The article identifies and evaluates the major determinants of demand uncertainty ,audience composition, critical acclaim and media coverage, whose management is key to entrepreneurial success. An in-depth historical case study of the controversial production, Jerry Springer the Opera, analyses the evolution of these three distinct sources of uncertainty and illustrates that they should not be treated in isolation since they interact in complex ways which change with time. The case study shows how the entrepreneurs involved used a multi-staged production process as a strategy to market test their product and to distribute their risks across agents and over time. The article therefore considers what contributed to both the successes and failures of these entrepreneurs as well as highlighting important strategic lessons for managing uncertainty in creative industries. [source] The Impact of Imperfect Processes on Production Run TimesDECISION SCIENCES, Issue 4 2000Tonya Boone ABSTRACT This paper investigates the interaction between the economics of production and imperfections in the production process. Specifically, this paper is the first to devise a model in an attempt to provide managers with guidelines to choose the appropriate production run times to buffer against both the production of defective items and stoppages occurring due to machine breakdowns. In addition to providing several structural properties of the model, we show that a manager will always incur a cost penalty when (s)he uses the results of two oft-cited models-the EMQ (Economic Order/Manufacturing Quantity) and the NR-E (No-Resumption, Exponential machine breakdown)-to determine production run times. [source] CAN THE HUMAN CAPITAL APPROACH EXPLAIN LIFE-CYCLE WAGE DIFFERENTIALS BETWEEN RACES AND SEXES?ECONOMIC INQUIRY, Issue 1 2007HUOYING WU Using data from the National Longitudinal Survey of Youth,1979 cohort (NLSY79), this paper shows the importance of postschool human capital investment in describing both gender and racial wage gaps. The empirical results suggest that male-female wage gaps, regardless of race, are mainly caused by gender differences in the human capital production process; generally, men gain more work experience and therefore have lower marginal costs of human capital production. Black-white lifetime wage differentials could partly result from higher implicit interest rates for blacks, while the deterioration of black males' relative economic status as they age can be attributed to higher depreciation rates of their human capital stock. (JEL J24, J30, C61) [source] Financial and Thermodynamic EquilibriumECONOMIC NOTES, Issue 3 2000Antonio Roma This paper explores general equilibrium asset pricing implications in a two-period model in which the production side explicitly describes the thermodynamic process unavoidably connected with production. We show that steady state of the production process, i.e. thermodynamic equilibrium, has a one-to-one correspondence with the absence of arbitrage possibilities. This provides an alternative definition of the absence of arbitrage. (J.E.L.: D5, G1, R3) [source] Educational production in EuropeECONOMIC POLICY, Issue 43 2005Ludger Wößmann SUMMARY Europe's schools Available data and recently developed estimation methods make it possible to assess school performance in terms of a production process, where ,inputs' of students, teachers, and resources are combined to create a very important ,output': the cognitive skills of students. This paper estimates the education production function using representative samples of middle-school students in 15 West European countries. The size of teaching classes is a particularly important feature of the educational production process because it can be relatively easily manipulated by policy makers. However, no statistically and economically significant class-size effect is detected by any of the evidence considered in this paper. The results suggest that, at least in the context of the resources and organizational structure of West European lower secondary education systems, expensive across-the-board reduction of class sizes is extremely unlikely to foster student learning. , Ludger Wößmann [source] Dynamic modelling of bacterial cellulose formationENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2009Michael Hornung Abstract The interest in cellulose produced by bacteria from surface cultures has increased steadily in recent years because of its potential for use in medicine and cosmetics. Unfortunately, the low yield of this production process has limited the commercial usefulness of bacterial cellulose. The aim of this paper is to show the effect of substrate mass transfer on the growth of the bacteria and on their physiological potential for product formation by means of a dynamic mathematical model. [source] Narratives as Cultural Tools in Sociocultural Analysis: Official History in Soviet and Post-Soviet RussiaETHOS, Issue 4 2000Professor James V. Wertsch An approach to sociocultural analysis based on the ideas of Vygotsky, Bakhtin, and others is used to provide the foundation for discussing narratives as "cultural tools." The production of official, state sponsored historical narratives is examined from this perspective, and it is argued that this production process may be shaped as much by dialogic encounters with other narratives as by archival information. These claims are harnessed to examine the production of post-Soviet Russian history textbooks, especially their presentation of the events surrounding the Russian Civil War of 1918,20. [source] Multilayer Amorphous-Si-B-C-N/,-Al2O3/,-Al2O3 Membranes for Hydrogen Purification,,ADVANCED ENGINEERING MATERIALS, Issue 6 2010Ravi Mohan Prasad Abstract The hydrogen and carbon monoxide separation is an important step in the hydrogen production process. If H2 can be selectively removed from the product side during hydrogen production in membrane reactors, then it would be possible to achieve complete CO conversion in a single-step under high temperature conditions. In the present work, the multilayer amorphous-Si-B-C-N/,-Al2O3/,-Al2O3 membranes with gradient porosity have been realized and assessed with respect to the thermal stability, geometry of pore space and H2/CO permeance. The ,-Al2O3 support has a bimodal pore-size distribution of about 0.64 and 0.045 µm being macroporous and the intermediate ,-Al2O3 layer,deposited from boehmite colloidal dispersion,has an average pore-size of 8,nm being mesoporous. The results obtained by the N2 -adsorption method indicate a decrease in the volume of micropores,0.35 vs. 0.75,cm3,g,1,and a smaller pore size ,6.8 vs. 7.4 Å,in membranes with the intermediate mesoporous ,-Al2O3 layer if compared to those without. The three times Si-B-C-N coated multilayer membranes show higher H2/CO permselectivities of about 10.5 and the H2 permeance of about 1.05,×,10,8 mol m,2 s,1 Pa,1. If compared to the state of the art of microporous membranes, the multilayer Si-B-C-N/,-Al2O3/,-Al2O3 membranes are appeared to be interesting candidates for hydrogen separation because of their tunable nature and high-temperature and high-pressure stability. [source] Heat Transport in Closed Cell Aluminum Foams: Application Notes,ADVANCED ENGINEERING MATERIALS, Issue 10 2009Jaime Lázaro Heat transport equations have been used to solve, by implementing the Finite Element Method (FEM), three different cases representative of the aluminium foams life: the production process (solidification in the molten state), post-production (water quenching heat treatments) and applications (fire barriers). [source] Inside the Locker Room: Male Homosociability in the Advertising IndustryGENDER, WORK & ORGANISATION, Issue 3 2009Michele Rene Gregory The use of the term homosociability by male employers and employees has been a key issue in the construction and maintenance of the gendered labour market, especially in senior-level jobs. Male homosociability encompasses the formal old boys' networks and informal clubs or meetings, as well as humour and banter, referred to metaphorically in this article as the locker room. This article examines the locker room and its resulting forms of socializing, socialization, communication and rituals found in the advertising industry. To gain a clearer understanding of how the locker room constructs workplace opportunities, this article draws upon qualitative research and analysis and examines major service occupations in the advertising industry and the executives who inhabit them. Studying the relationship between the locker room and the production process provides additional perspectives on service work in the corporate sector, occupations and gender inequality. [source] Performing Women: The Gendered Dimensions of the UK New Research EconomyGENDER, WORK & ORGANISATION, Issue 5 2007Catherine Fletcher This article explores the development and maintenance of familiar gendered employment patterns and practices in UK universities, which are exemplars of new modes of knowledge production, commodification and marketization. After discussing in detail the evidence of gender discrimination in UK higher education and the changes in the academic labour process consequent to the incorporation of universities, at least at the policy level, into the ,knowledge economy', institution-specific data is used to highlight the gendered aspects of the research economy from the three intermeshing perspectives of research culture, research capital and the research production process. This nexus is constructed in such a way as to systematically militate against women's full and equal involvement in research. Lack of transparency, increased competition and lower levels of collegiate activity coupled with networking based on homosociability are contributing to a research production process where women are marginalized. [source] Efficiency and TFP Growth in the Spanish Regions: The Role of Human and Public CapitalGROWTH AND CHANGE, Issue 2 2003Maria del Mar Salinas Jiménez Once estimates of efficiency are obtained, the aim of this paper is to analyze the effects of human and public capital on growth in terms of their impact on Total Factor Productivity (TFP). Public capital is believed to increase the productivity of the private factors of production whereas human capital is thought to contribute to the production process as an additional input and to have a dynamic influence on growth through its impact on technological innovation (shifts in the production frontier) and technological diffusion (movements toward the frontier), which are the components of this TFP measure. Considering inefficiencies will then allow the effects of these variables on TFP growth to be estimated via technological progress and efficiency gains. [source] REVIEW ARTICLE: An improved manufacturing process for Xyntha/ReFacto AFHAEMOPHILIA, Issue 5 2010B. KELLEY Summary., ReFacto® Antihemophilic Factor is a second-generation antihaemophilia A product manufactured using a process that includes therapeutic grade human serum albumin (HSA) in the cell culture medium, but is formulated without HSA as a stabilizer. Even though this second-generation antihaemophilia product has a good safety profile, a programme was implemented to eliminate all animal- and human-derived raw materials from the production process, thus producing a third-generation product. To that end, HSA has been removed from the master and working cell banks and from the culture medium. The hybridoma-derived monoclonal antibody formerly used in the purification process has been replaced by a chemically synthesized affinity peptide, and a virus-retaining filtration step has been added to enhance the clearance of large viruses, such as retroviruses. The purification process has been validated for the removal of a panel of model viruses and provides significant clearance of all viruses tested. Host cell- and process-derived impurity removal validations also were conducted, including host cell DNA and protein, in addition to the affinity peptide. Compared with the product manufactured according to the original process, these changes had no detectable effect on the structural integrity, stability or clinical efficacy of this antihaemophilia A product. The product produced by the improved manufacturing process is named XynthaÔ/ReFacto AF. [source] Safety and efficacy of a plasma-derived monoclonal purified factor VIII concentrate during 10 years of follow-upHAEMOPHILIA, Issue 6 2007E. P. MAUSER-BUNSCHOTEN Summary., In 1995, AAFACT®, a new monoclonal purified factor VIII concentrate (FVIII), derived from human plasma, was introduced in the Netherlands. The monoclonal purification based production process includes a viral inactivation step by solvent/detergent treatment. Products manufactured according to this procedure, for example Hemofil M® are used worldwide. The aim of the present study was to assess inhibitor development in a large cohort of previously treated patients (PTPs) who were followed up for 10 years. In addition, efficacy, HIV and hepatitis C virus (HCV) transmission, and allergic reactions were monitored. All 165 patients with severe haemophilia A (FVIII < 1%) known at the van Creveldkliniek who ever used AAFACT® during the period from October 1995 to September 2005 were included. Two of them were previously untreated patients (PUPs) and two others had <50 exposure days. Data on FVIII consumption, number of exposures, bleedings and hospitalization days were collected from start of AAFACT® until last clinical and laboratory evaluation while on this product. At the end of follow-up, 91 patients were still using this plasma-derived FVIII. Median age at start of follow-up was 26 years (range 1,52). None of the patients reported lack of efficacy. Median FVIII consumption per patient during follow-up was 2058 IU kg,1 bodyweight per year, and median number of exposures was 148 per year. During 1029 patient-years of follow-up, one inhibitor was diagnosed in a previously treated patient PTP. This patient developed high titre inhibitor following surgery for which he, during 1 week, had been treated with continuous infusion with recombinant FVIII. No inhibitor occurred during 68 cases of surgery using continuous infusion with AAFACT®. No viral transmissions or other adverse events occurred during 10 years of follow-up; AAFACT® appeared to be an effective and safe FVIII product. [source] European data of a clinical trial with a sucrose formulated recombinant factor VIII in previously treated haemophilia A patientsHAEMOPHILIA, Issue 2002C. Rothschild Summary., To increase the safety of antihaemophilic treatment, the production process of full-length recombinant factor VIII (FVIII) KOGENATE® Bayer (Kogenate®FS)has been modified. Human albumin is no longer added as stabilizer during purification and in final formulation. Instead, the new KOGENATE® Bayer production process uses sucrose as a stabilizer in the formulation and adds solvent/detergent virus inactivation step. An European clinical trial was carried out in Germany and France in previously treated patients with severe haemophilia A who had more than 100 exposure days to exogenous FVIII. Pharmacokinetic data was analysed according to one-stage and chromogenic assays. Efficacy and safety during home therapy and in surgical procedures were evaluated; inhibitor formation was carefully monitored. Safety and efficacy were evaluated in 33 European patients for 24 months. Patients received more than 13 million IU KOGENATE® Bayer. Over 75% of patients accrued more than 100 exposure days with the new product. Of 875 bleeding episodes, 90.7% were treated with 1 or 2 infusions and 75.8% of responses to treatment were rated as ,excellent' or ,good'. Prophylactic treatment was the most common mode of therapy (60.7% of infusions). The product was well-tolerated and FVIII recovery studies were consistent throughout the study period. Only 0.26% of adverse events were reported to be drug related. No evidence of de novo inhibitor formation was observed. Overall, KOGENATE® Bayer was efficacious, safe and well-tolerated for the treatment of haemophilia A in multitransfused patients. [source] Stress-adapted numerical form finding of pre-stressed surfaces by the updated reference strategyINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 2 2005R. Wüchner Abstract In this paper we present the updated reference strategy for numerical form finding of pre-stressed membranes, which is based on standard finite element discretization. The singularities of the inverse problem are regularized by a homotopy mapping. A projection scheme is proposed where anisotropic pre-stress is defined with respect to an additional reference plane, which reflects the initially developable surface of membrane strips in the production process. Physically problematic combinations of edge geometry and surface stress are solved by a self-adaptive stress correction scheme. The algorithm is based on a local criterion derived from differential geometry. Several examples illustrate the success of each idea and implementation. Copyright © 2005 John Wiley & Sons, Ltd. [source] Fluid dynamic numerical simulation coupled with heat transfer and reaction in the tubular reactor of industrial cracking furnacesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2010Chufu Li Abstract The thermal cracking furnace is the heart of the ethylene production process in a petrochemical plant. This paper presents a comprehensive mathematical model containing equations for mass, momentum and heat transfer combined with Kumar molecular kinetic model to describe dynamic behaviors of fluid flow, heat transfer and reaction in the tubular reactor of thermal cracking furnaces. The ,flow-reaction' decomposition strategy is adopted to solve the complex model for implementing the fluid dynamic simulation coupled with heat transfer and reaction in the tubular reactor by a conventional procedure. The proposed mathematical model and the decomposition algorithm are successfully applied to the fluid dynamic simulation in the tubular reactor of a millisecond industrial cracking furnace. The results of dynamic simulation reveal the various transient behaviors of fluid flow, temperature change and species content variation in the tubular reactor under the step disturbance of inlet feedrate. Finally, the performance of the decomposition algorithm is also investigated. Copyright © 2009 John Wiley & Sons, Ltd. [source] Fuzzy decision support for the control of detergent productionINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 8 2001Magne Setnes This paper describes a fuzzy decision support system (DSS) for the control of a detergent production process. The application has been carried out at a real-world, large-scale industrial production plant in the Netherlands, where a large variety of powder-based detergents for industrial users are produced in a spray drying process. The system consists of several fuzzy rule bases that model the control actions of experienced process operators in response to different quality deviations of the product. A hierarchical architecture of the fuzzy system is introduced to cope with the complexity. A fuzzy supervisor is used to deal with process constraints and to activate the applicable rule bases when control actions are needed. In this way, a system is obtained that enables the control of the process within stricter quality bounds than those applied by human operators alone. During in-production evaluation, the average improvement in the quality parameters for all product classes was above 30 percent. Copyright © 2001 John Wiley & Sons, Ltd. [source] Stochastic analysis of crude oil procurement and processing under uncertain demand for bunker fuel oilINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 5 2006Bernardo Zimberg Abstract Bunker fuel oil (ifo), one of the products of petroleum refining, has a strong impact in the production process because it drives the availability of heavy residues that depend on the crude quality. A simplified stochastic model for the Administración Nacional de Combustibles Alcohol y Portland refinery, based on the uncertainty of the demand for ifo, is proposed for comparison with the current approach of deterministic demand. In this model, the benefits of the production process are maximized, taking decisions on the more suitable raw material, intermediate products and final blends in order to fulfill quality and demand requirements of final products. A specific case is analyzed where the maximum benefit is achieved when the most expensive crude quality is purchased, due to a lack of incentive to produce extra amounts of heavy fuel oil that must be exported at a non-attractive price. Results are compared with the solution of a deterministic model with mean demand. In addition, the stochastic model solution depicts how the refinery should operate for each scenario of ifo demand. [source] Toughening of basalt fiber-reinforced composites with a cyclic butylene terephthalate matrix by a nonisothermal production methodADVANCES IN POLYMER TECHNOLOGY, Issue 2 2010J. Baets Abstract The interest in thermoplastic composites is growing because of their advantages over thermosets, as well as their recyclability and higher toughness. The melt viscosity of thermoplastic polymers is very high, which makes fiber impregnation difficult. This difficulty can be overcome by the in situ polymerization with cyclic butylene terephthalate (CBT). However, this leads to a brittle polybutyleneterephthalate when isothermal RTM-production is applied. To solve this problem, a nonisothermal production process for composites with CBT as matrix material was developed and the influence on the toughness was investigated. In the nonisothermal production process, different cooling rates were applied to examine their influence on the toughness of the produced composites. The difference in composites properties was related to the difference in the degree of crystal perfection, which was investigated by differential scanning calorimetry. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 29:70,79, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20176 [source] Development of a mathematical model for Bacillus circulans growth and alkaline protease production kineticsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2009Chaganti Subba Rao Abstract BACKGROUND: An unstructured mathematical model was developed to understand information on the relationship between Bacillus circulans growth and metabolism-related protease production (using logistic and Luedeking,Piret equations respectively) in a batch reactor with respect to glucose consumption and fermentation time. The objective was to develop an indispensable tool for the optimisation, control, design and analysis of alkaline protease production. RESULTS: Biomass growth and enzyme production titres changed with a change in substrate concentration. Modelling analysis of biomass and enzyme production titres at different substrate concentrations revealed significant accuracy in terms of statistical consistency and robustness with respect to fermentation kinetic profiles. CONCLUSION: With the B. circulans strain used, an economic protease yield (2837 × 103 U g,1) with respect to biomass and glucose ratio was achieved at low substrate concentration (10 g L,1). The developed model could be effectively utilised for designing, controlling and up-scaling the protease production process in high-density fermentation in selected bioreactors with statistical consistency. Copyright © 2008 Society of Chemical Industry [source] Improvement of a fed-batch process for high level xylanase production by a Bacillus strainJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2001Gerhard Schneider Abstract In this paper, the improvement of a fed-batch fermentation from the point of view of an industrial xylanase production process is described. The Bacillus strain chosen for this study is able to produce high quantities of a xylanase that is suitable to be used as bleach boost agent in chlorine-free bleaching sequences of paper pulp. It was found that xylo-oligosaccharides (hydrolysis products from xylan by xylanase action) were indispensable for induction of the enzyme synthesis, but that their presence in quantities of only 0.1,g,dm,3 xylose equivalents led to catabolite repression. A substrate-limited fed-batch process, that is the most adapted, was furthermore improved with regard to nutrient requirement of the microorganism, especially the nitrogen source. A process with constant supply of a culture medium containing xylan, peptone and mineral nitrogen was able to produce 20,240,nkat,cm,3 with a productivity of 910,nkat,cm,3,h,1, which places the process among the best ever reported. © 2001 Society of Chemical Industry [source] Statistical analysis of catalyst degradation in a semi-continuous chemical production processJOURNAL OF CHEMOMETRICS, Issue 8 2001Eleftherios Kaskavelis Abstract The effect of decaying catalyst efficacy in a commercial-scale, semi-continuous petrochemical process was investigated. The objective was to gain a better understanding of process behaviour and its effect on production rate. The process includes a three-stage reaction performed in fixed bed reactors. Each of the three reaction stages consists of a number of catalyst beds that are changed periodically to regenerate the catalyst. Product separation and reactant recycling are then performed in a series of distillation columns. In the absence of specific measurements of the catalyst properties, process operational data are used to assess catalyst decay. A number of statistical techniques were used to model production rate as a function of process operation, including information on short- and long-term catalyst decay. It was found that ridge regression, partial least squares and stepwise selection multiple linear regression yielded similar predictive models. No additional benefit was found from the application of non-linear partial least squares or Curds and Whey. Finally, through time series profiles of total daily production volume, corresponding to individual in-service cycles of the different reaction stages, short-term catalyst degradation was assessed. It was shown that by successively modelling the process as a sequence of batches corresponding to cycles of each reaction stage, considerable economic benefit could be realized by reducing the maximum cycle length in the third reaction stage. Copyright © 2001 John Wiley & Sons, Ltd. [source] Connective Ethnography for the Exploration of e-ScienceJOURNAL OF COMPUTER-MEDIATED COMMUNICATION, Issue 2 2007Christine Hine E-science comprises diverse sites, connected in complex and heterogeneous ways. While ethnography is well established as a way of exploring the detail of the knowledge production process, some strategic adaptations are prompted by this spatial complexity of e-science. This article describes a study that focused on the biological discipline of systematics, exploring the ways in which use of a variety of information and communication technologies has become a routine part of disciplinary practice. The ethnography combined observation and interviews within systematics institutions with mailing list participation, exploration of web landscapes, and analysis of expectations around information and communications technologies as portrayed in policy documents. Exploring connections among these different activities offers a means of understanding multiple dimensions of e-science as a focus of practice and policy. It is important when studying e-science to engage critically with claims about the transformative capacity of new technologies and to adopt methodologies that remain agnostic in the face of such claims: A connective approach to ethnography offers considerable promise in this regard. [source] A NEW METHOD FOR ELLAGIC ACID PRODUCTION FROM POMEGRANATE HUSKJOURNAL OF FOOD PROCESS ENGINEERING, Issue 4 2008JINGJING LU ABSTRACT Pomegranate (Punica granatum L.) husk, a by-product of the pomegranate juice industry, is an inexpensive and abundant source of ellagic acid. Ellagic acid is widely used as functional food for its physiological functions. It is the breakdown product of ellagitannins. To date, the preparation of ellagic acid from pomegranate husk has not been reported. This article reports a new process for ellagic acid production from pomegranate husk by extraction of tannins followed by acid hydrolysis and purification by extraction and recrystallization. Several tests were conducted to obtain optimum conditions including extraction of tannins by varying solvents, acid concentration and reaction time for acid hydrolysis and the volume of methanol used for purification. Ellagic acid (3.5 g) with 90% purity from 100 g pomegranate husk was obtained. This new method is easy to scale up. All equipment used in this production process is widely used in food processing industry. The cost of production is low. It is suitable for industrial applications. PRACTICAL APPLICATIONS The production of ellagic acid is easier and the yield and purity of ellagic acid produced this way are higher than before. This method can be used not only for experiment in laboratory but also for industrial applications. The material , pomegranate husk , is a by-product of the pomegranate juice industry, so it is very cheap and easy to get. High-purity ellagic acid produced this way is sold to many companies back home and abroad. It is used as food additive and cosmetic material because of its antioxidant activity and whiteningfunction. The toxicity of pomegranate husk is lower than that of gallnut, which has been the main material of ellagic acid production in the past. Reagents are common and inexpensive; some of them are reusable. [source] APPLICATION OF EXPERIMENTAL DESIGN METHOD TO THE OIL EXTRACTION FROM OLIVE CAKEJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2 2009SMAIL MEZIANE ABSTRACT Olive cake is an important solid waste of the olive oil production. It still contains a certain quantity of oil that can be recovered by means of solvent extraction. In this study, two-level full factorial design was performed to evaluate the effects of four variables and their interactions on the oil extraction by the ethanol 96.0% in a batch reactor. The variables included size of particles, temperature, and time of contact and solvent-to-solids ratio. The statistical analysis of the experimental data showed that the extracted oil mass depends on all the examined variables. It also depends on the interactions between size of particles and solvent-to-solid ratio and size of particles and temperature. The experimental data were in good agreement with those predicted by the model. PRACTICAL APPLICATIONS Olive cake is solid waste of the olive oil industry that is available in large amounts in many Mediterranean countries and at very low cost. It can be treated or valorized, enabling at the same time the solution to environmental problems caused by the olive oil production process. The economic interest that it presents is especially because of the residual oil that it contains and that can be recovered by solvent extraction. However, this solid,liquid extraction depends on several parameters: the ones inherent to the products (structure and properties of the sample, nature of extraction solvent); and the others to the extraction process (time of contact, temperature of extraction, solvent-to-solid ratio, stirring velocity). The experimental design method enables to determine the most important variables and their interaction in the extraction process at the same time performing a low number of experiments. [source] | ||||||||||||||||||||||||||||||||||